8. Trimeric G Protein Signaling

Question 0

what are the 2 things required to stimulated adenylyl cyclase?

Answer 0

hormone (ligand) & GTP

Question 1

2 major signaling mechanisms that a cell can use?

Answer 1

1. direct phosphorylation

2. signaling via nucleotide-triphosphate-binding to a G protein

Question 2

GTPase enzyme kinetics

Answer 2

has a low Km (high affinity)

Question 3

3 subunits of G proteins?

Answer 3

alpha
beta
gamma

Question 4

G-as

Answer 4

defines the majority of G protein function

activates AC

Question 5

G-aq

Answer 5

activates PLC-beta

Question 6

What is the rate limiting step for a reaction with a G protein?

Answer 6

dissociation of GDP from the alpha subunit

Question 7

G protein, by default, is in what form?

Answer 7

OFF (T-form)

second step proceeds 10x faster when a ligand is not bound to the GPCR

Question 8

example of G protein signaling: epinephrine

Answer 8

E binds receptor
GDP dissociates, replaced by GTP, activates Gas
Gas activates AC
AC catalyzes formation of cAMP
cAMP activates PKA
PKA phosphorylates cellular proteins that cause the cellular response to E

Question 9

GPCR structure

Answer 9

7 transmembrane domains

Question 10

which cytoplasmic loop interacts with the G protein the most?

Answer 10

3rd

receptor is buried within the membrane

Question 11

what does AC do?

Answer 11

catalyze the formation of cAMP

Question 12

What does PLC do?

Answer 12

break PIP2 into IP3 & DAG

Question 13

What activates PLPC-beta

Answer 13

G-alpha-q

Question 14

Secondary messengers examples (4)

Answer 14

cAMP
IP3
DAG
Calcium

Question 15

what does cAMP do?

Answer 15

acts as a secondary messenger to protein kinases i.e. cAMP dependent protein kinase

Question 16

what does IP3 do?

Answer 16

release calcium from ER stores

Question 17

What does DAG do?

Answer 17

activates PKC

Question 18

calmodulin structure? and what does it do?

Answer 18

4-calcium holding protein, enables safe Ca storage & quick Ca release

activates Ca calmodulin dependent kinase

Question 19

what do multifunctional kinases do?

Answer 19

pass and amplify signal

Question 20

what do tyrosine kinases do?

Answer 20

deliver signal to its target destination

Question 21

PKA strucutre?

Answer 21

2 regulatory subunits

2 catalytic subunits

Question 22

how does cAMP activate PKA?

Answer 22

2 cAMPs per regulatory subunit, bind to substrate sites, causing regulatory subunits to dissociate from the catalytic subunits–conformational change to the catalytic subunits to make them active and ready to find proteins

Question 23

what does PKC do?

Answer 23

controls phosphorylation of certain serine and threonine residues on select proteins and eventually elicit a cellular response

Question 24

CAMK II

Answer 24

serine/threonine protein kinase

integral in the learning process

Question 25

as the frequency of calcium waves increases within a cell, what happens to CAM KII?

Answer 25

more units of CAM KII are activated, increasing the overall activity of CAM KII